Mechanism of a dual-phase Ti-Nb alloy exhibiting near-linear elastic deformation

In this work, the underlying mechanism responsible for the near-linear elastic deformation behavior of a dual-phase Ti-Nb alloy consisting of β and α″ phase with large recoverable strain was systematically elucidated. Based on in situ synchrotron X-ray diffraction (SXRD) analyses, it was found that besides intrinsic elastic deformation, a slight reversible β ↔ α″ stress-induced martensitic (SIM) transformation, which proceeded in a consecutive mode under the retarding effect of micro-defects, took place during the near-linear elastic deformation. After unloading, a small amount of residual macroscopic strain remained in the specimen due to the incomplete reverse α″ → β transformation on unloading. The high near-linear elastic deformability of the cold drawing (CD) Ti-Nb alloy has been revealed to be attributed to the coupling actions of intrinsic elasticity as well as the consecutive and reversible β ↔ α″ SIM transformation. Our research may contribute to a new avenue for the design and development of novel dual-phase Ti-based alloys with desirable elastic deformability.